836 THE POPULAR SCIENCE MONTHLY. 



walls, should not "be destroyed. These walls should be decorated, 

 not with paper and paint, but with porous, non-conducting sub- 

 stances, such as woolen drapery. The outer walls on the side 

 nearest to the inner surface should be hollowed throughout, thus 

 constituting a double wall, with a space of about four inches be- 

 tween the two walls. A heating contrivance of whatever descrip- 

 tion may be found most expedient or economical should be placed 

 in the basement of the house. A warm-air chamber or shaft trav- 

 eling round the base of the outer walls should supply to the hollow 

 in the walls air taken from the outside and warmed at the point 

 of admission into the wall to a temperature of from 100 to 120 

 Fahr. This should maintain the temperature of the inner wall at 

 from 80 to 90 Fahr. Then, he considers, the walls will radiate 

 sufficient heat through the rooms to enable the inhabitants to con- 

 stantly open the doors and windows, and to breathe cold, fresh, 

 outer air without inconvenience. As a rule, fires will be unneces- 

 sary, dampness will be completely banished from the house, and 

 to maintain some moisture in the air it would, he thinks, be expe- 

 dient to decorate the house with numerous evergreen plants. The 

 inhabitants should then be able to benefit by unlimited ventila- 

 tion, and could breathe pure, cold, and fresh air coming upon 

 them directly from the outside. Report of the London Lancet 

 Sanitary Commission. 



The address of T. Baldwin Spence, President of the Biological Section of the 

 Australian Association, dealt with the fresh-water and terrestrial fauna of Tas- 

 mania, and the introduction of the present animals of Australia and the way their 

 descendants had become distributed. The struthious birds the ostriches, emus, 

 cassowaries, and kiwis were, with the exception of the African ostrich, which 

 ranged into Arabia, confined to the southern hemisphere, while they were sup- 

 posed to have originated in the northern hemisphere and migrated southward. 

 But by this hypothesis there were great difficulties in explaining how the struthi- 

 ous birds reached Australia and New Zealand without being accompanied by pla- 

 cental mammals. Also, the struthious birds of New Zealand, including the lately 

 extinct moas, were smaller, and made a nearer approach to the flying birds, from 

 which the struthious birds were descended, than did any of the others, and they 

 should expect to find the least altered forms near the place of origin. The tina- 

 mus of Central and South America, although flying birds, resembled the New Zea- 

 land struthious birds in several particulars ; and as a former connection between 

 New Zealand and South America was shown by the plants, the frogs, and the land 

 shells, it seemed more probable that the struthious birds of Australasia originated 

 in the neighborhood of New Zealand from flying birds related to the tinamus, and 

 that they spread thence into Australia and New Guinea, rather than that they 

 should have migrated southward from Asia. Probably the ostriches of Africa and 

 South America have a different line of descent from the struthious birds of Aus- 

 tralasia, and might have originated from swimming birds in the northern hemi- 

 sphere. 



